Monday 16 July 2007 19.05 EDT
First published on Monday 16 July 2007 19.05 EDT

Laboratory tests have shown that an ingredient commonly used in curries may protect against Alzheimer's disease by boosting the brain's natural ability to mop up nerve-destroying protein plaques associated with the condition.

The work was conducted by researchers at the Greater Los Angeles Veterans Affairs Medical Centre at the University of California after epidemiological studies suggested that diet might explain why Alzheimer's disease is so rare in India.

Researchers led by Milan Fiala extracted immune cells from healthy people and patients with Alzheimer's disease, and tested how well they absorbed and destroyed protein plaques, which many scientists believe to be the primary cause of Alzheimer's. They found that immune cells from Alzheimer's patients were worse at clearing up the plaques than cells taken from healthy people.

But when the team added an ingredient called bisdemethoxycurcumin, an active ingredient found in turmeric root, the immune cells became more active.

Further tests showed that the ingredient altered the expression of key genes in the immune cells, overcoming the damage that had originally weakened them.

The researchers said it was too early to know how the ingredient worked in the body and whether a lifetime of eating curries had any preventative effect against Alzheimer's. Studies were continuing to see whether a supplement is effective.

"It's not such a far-fetched idea that this could lead to a useful drug," said Dr Fiala, whose study appears in Proceedings of the National Academy of Sciences.